TEHRAN, Iran — Police officers used sticks and tear gas to force back thousands of demonstrators under plumes of black smoke in the capital on Saturday, a day after Iran's supreme leader, Ayatollah Ali Khamenei, said there would be "bloodshed" if street protests continued over the disputed presidential election.
Separately, state-run media reported that three people were wounded when a suicide bomber attacked the Tehran shrine of Ayatollah Ruhollah Khomeini in the southern part of the city, several miles from the scheduled protests. The report of the blast could not be independently confirmed.
The violence unfolded on a day of extraordinary tension across Iran. The opposition leader, Mir Hussein Moussavi, appeared at a demonstration in southern Tehran and called for a general strike if he were to be arrested.
"I am ready for martyrdom," he said.
Moussavi again called for nullifying the election's results, and opposition protesters swore to continue pressing their claims of a stolen election against Iran's embattled and increasingly impatient clerical leadership in Iran's worst crisis since the 1979 Islamic Revolution.
In Washington, President Barack Obama called the government's reaction "violent and unjust," and warned again that the world was watching what happened in Tehran.
Iran's divisions played out on the streets. Regular security forces stood back and urged protesters to go home and avoid bloodshed, while the feared pro-government militia, the Basij, beat protesters with clubs and, witnesses said, electric prods.
In some places, the protesters pushed back, rushing the militia in teams of hundreds: At least three Basijis were pitched from their motorcycles, which were then set on fire. The protesters included many women, some of whom berated as "cowards" men who fled the Basijis.
There appeared to be tens of thousands of protesters in Tehran, far fewer than the mass demonstrations early last week.The street violence appeared to grow more intense as night fell, and there were unconfirmed reports of multiple deaths. A BBC journalist at Enghelab (Revolution) Square reported seeing one person shot by security forces. An amateur video posted on YouTube showed a woman bleeding to death after being shot by a Basiji, the text posted with the video said.
"If they open fire on people and if there is bloodshed, people will get angrier," said a protester, Ali, 40. "They are out of their minds if they think with bloodshed they can crush the movement."
There had been varying reports in the hours leading up to the opposition rally about whether it would be called off in the face of the state's threatened crackdown. State television reported that Moussavi had called it off, but some of his supporters, posting on social networking sites, urged demonstrators to gather.
Journalists were banned from leaving their offices to report on the protests.
Asking for annulment
A letter from Moussavi published on one of his Web sites late Saturday repeated his demand for the election to be annulled.
"The Iranian nation will not believe this unjust and illegal" act, he said in the letter, which was addressed to the powerful Guardian Council, a panel of clerics that oversees and certifies election results. Making his case for electoral fraud, he charged that thousands of his representatives had been expelled from polling stations and some mobile polling stations had ballot boxes filled with fake ballots.
In a long and hard-line sermon on Friday, Khamenei declared the June 12 election of President Mahmoud Ahmadinejad valid and warned that demonstration leaders "would be responsible for bloodshed and chaos" if demonstrations continued.
Regional analysts said that, by calling for an end to the rallies, Khamenei had inserted himself directly into the confrontation, invoking his own prestige and that of Iran's clerical leaders. But his speech also laid the groundwork to suppress the opposition movement with a harder hand, characterizing any further protests as against the Islamic republic itself.
Iran's National Security Council reinforced Khamenei's warning Saturday, state media reported, telling Moussavi to "refrain from provoking illegal rallies."
The demand came in a letter from the head of the council after a formal complaint by Moussavi that law enforcement agencies had failed to protect protesters.
"It is your duty not to incite and invite the public to illegal gatherings; otherwise, you will be responsible for its consequences," the letter said, according to state media.